<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>圆角边框</title>
    <style>
        div {
            height: 200px;
            width: 200px;
            background-color: #333;
            /* 实现盒子圆角 */
            border-radius: 20px;
            /* border-radius: 20%; */
            /* border-radius: 10px 20px 30px 40px; */
        }
    </style>
</head>

<body>
    <div></div>
</body>

</html>